1. Field of the Invention
This invention relates to check valves, and relates more specifically to a check valve for needleless medical usage.
2. Description of the Background Art
Presently, there are many types of check valves which are designed to control the one-way flow of a fluid therethrough. One common type of check valve comprises a valve element, such as a ball or spring biased valve stem, reciprocatingly positioned within a valve body providing a fluid passageway. The flow of fluid in one direction through the valve body is permitted upon displacement of the stem as it flows around the valve stem to exit the valve body. In the opposite direction, however, the fluid pressure along with the spring forces the valve stem against a valve seat, thereby inhibiting, or checking the flow of fluid therethrough. In this manner, this type of check valve effectively provides that fluid can flow only in one direction through the check valve. An example of this type of valve is found in U.S. Pat. No. 5,349,984, the disclosure of which is incorporated by reference herein.
Check valves employing an elastomeric stem without the use of a spring are described in U.S. Pat. No. 3,831,629, the disclosure of which is incorporated by reference herein. Other check valves employing umbrella or disk-like elastomeric elements are described in the following U.S. Pat. Nos. 5,992,462; 4,499,916 and 4,369,812, the disclosures of which are incorporated by reference herein. Some check valves employ elastically deformable diaphragm-like elements as described in U.S. Pat. No. 6,390,120, the disclosure of which is incorporated by reference herein. Another check valve employing conical or hollow elastomeric elements where fluid flow is arranged to pass through the element itself is described in U.S. Pat. Nos. 5,573,516 and 5,746,414, the disclosures of which are incorporated by reference herein. Some of the designs described above allow for bi-directional fluid flow if accessed by the appropriate connector such as a luer fitting commonly used in the medical fluid delivery field.
There is a need in the industry to provide a reliable and economical check valve providing a reliable seal when checked by very low back pressures such as low fractions of pounds per square inch (PSI) while sealing at high back pressures, preferably in the range of 10-100 PSI. There is also a need for check valves that allow for an economical way to accommodate various preset opening or cracking pressure conditions. Most prior art valves of this nature employ springs that have varying spring properties, resulting in a check valve that provides different opening pressures without any component change.
More particularly, current pressure relief valves employ metal springs for accurate opening pressure settings. The presence of metal in an I.V. line presents possible contamination dangers from corrosion or metallic particles. Elimination of metal springs is therefore highly desirable. Check valves equipped with non-metal resilient sealing elements are designed for a specific opening pressure. The variability of this valve characteristic is therefore not easily achieved.
Most valves that are designed to seal at low pressures, such as disc valves, do not normally allow for high flow or bi-directional flow. Therefore, there exists a need in the industry to provide a check valve that accommodates relatively high fluid flow when unchecked.
Further, some valves with elastomeric elements where fluid flow is arranged to pass through the element itself have a possibility of particulate contamination. Molding of small check valve elastomeric components commonly include small openings for fluid to pass through. Such openings are created by cores of very small dimensions. These core features could be relatively easily damaged and could therefore cause flash and result in small particles of flash potentially breaking off and contaminating the fluid flow.
Therefore, it is an object of this invention to provide an improvement which overcomes the aforementioned inadequacies of the prior art devices and provides an improvement which is a significant contribution to the advancement of the check valve art.
Another object of this invention is to provide a check valve employing an elastomeric valve element that is economical to manufacture and assemble to achieve valves with different possible cracking pressure.
Another object of this invention is to provide a check valve that allows bi-directional high fluid flow when cracked.
Another object of this invention is to provide a check valve that maintains a seal when checked even at very low back pressures.
Another object of this invention is to provide a check valve that maintains a seal when checked even at high back pressures.
The foregoing has outlined some of the pertinent objects of the invention. These objects should be construed to be merely illustrative of some of the more prominent features and applications of the intended invention. Many other beneficial results can be attained by applying the disclosed invention in a different manner or modifying the invention within the scope of the disclosure. Accordingly, other objects and a fuller understanding of the invention may be had by referring to the summary of the invention and the detailed description of the preferred embodiment in addition to the scope of the invention defined by the claims taken in conjunction with the accompanying drawings.